machined: Move image discovery logic into src/shared, so that we can make use of it from nspawn

2 files changed, 380 insertions, 0 deletions

diff --git a/src/shared/machine-image.c b/src/shared/machine-image.c
new file mode 100644
index 000000000..51f89d592
--- /dev/null
+++ b/src/shared/machine-image.c
@@ -0,0 +1,325 @@
+/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
+
+/***
+  This file is part of systemd.
+
+  Copyright 2013 Lennart Poettering
+
+  systemd is free software; you can redistribute it and/or modify it
+  under the terms of the GNU Lesser General Public License as published by
+  the Free Software Foundation; either version 2.1 of the License, or
+  (at your option) any later version.
+
+  systemd is distributed in the hope that it will be useful, but
+  WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+  Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public License
+  along with systemd; If not, see <http://www.gnu.org/licenses/>.
+***/
+
+#include <sys/statfs.h>
+
+#include "strv.h"
+#include "utf8.h"
+#include "btrfs-util.h"
+#include "path-util.h"
+#include "machine-image.h"
+
+static const char image_search_path[] =
+        "/var/lib/machines\0"
+        "/var/lib/container\0"
+        "/usr/local/lib/machines\0"
+        "/usr/lib/machines\0";
+
+Image *image_unref(Image *i) {
+        if (!i)
+                return NULL;
+
+        free(i->name);
+        free(i->path);
+        free(i);
+        return NULL;
+}
+
+static int image_new(
+                ImageType t,
+                const char *pretty,
+                const char *path,
+                const char *filename,
+                bool read_only,
+                usec_t crtime,
+                usec_t mtime,
+                Image **ret) {
+
+        _cleanup_(image_unrefp) Image *i = NULL;
+
+        assert(t >= 0);
+        assert(t < _IMAGE_TYPE_MAX);
+        assert(pretty);
+        assert(filename);
+        assert(ret);
+
+        i = new0(Image, 1);
+        if (!i)
+                return -ENOMEM;
+
+        i->type = t;
+        i->read_only = read_only;
+        i->crtime = crtime;
+        i->mtime = mtime;
+
+        i->name = strdup(pretty);
+        if (!i->name)
+                return -ENOMEM;
+
+        if (path)
+                i->path = strjoin(path, "/", filename, NULL);
+        else
+                i->path = strdup(filename);
+
+        if (!i->path)
+                return -ENOMEM;
+
+        path_kill_slashes(i->path);
+
+        *ret = i;
+        i = NULL;
+
+        return 0;
+}
+
+static int image_make(
+                const char *pretty,
+                int dfd,
+                const char *path,
+                const char *filename,
+                Image **ret) {
+
+        struct stat st;
+        bool read_only;
+        int r;
+
+        assert(filename);
+
+        /* We explicitly *do* follow symlinks here, since we want to
+         * allow symlinking trees into /var/lib/container/, and treat
+         * them normally. */
+
+        if (fstatat(dfd, filename, &st, 0) < 0)
+                return -errno;
+
+        read_only =
+                (path && path_startswith(path, "/usr")) ||
+                (faccessat(dfd, filename, W_OK, AT_EACCESS) < 0 && errno == EROFS);
+
+        if (S_ISDIR(st.st_mode)) {
+
+                if (!ret)
+                        return 1;
+
+                if (!pretty)
+                        pretty = filename;
+
+                /* btrfs subvolumes have inode 256 */
+                if (st.st_ino == 256) {
+                        _cleanup_close_ int fd = -1;
+                        struct statfs sfs;
+
+                        fd = openat(dfd, filename, O_CLOEXEC|O_NOCTTY|O_DIRECTORY);
+                        if (fd < 0)
+                                return -errno;
+
+                        if (fstatfs(fd, &sfs) < 0)
+                                return -errno;
+
+                        if (F_TYPE_EQUAL(sfs.f_type, BTRFS_SUPER_MAGIC)) {
+                                BtrfsSubvolInfo info;
+
+                                /* It's a btrfs subvolume */
+
+                                r = btrfs_subvol_get_info_fd(fd, &info);
+                                if (r < 0)
+                                        return r;
+
+                                r = image_new(IMAGE_SUBVOLUME,
+                                              pretty,
+                                              path,
+                                              filename,
+                                              info.read_only || read_only,
+                                              info.otime,
+                                              0,
+                                              ret);
+                                if (r < 0)
+                                        return r;
+
+                                return 1;
+                        }
+                }
+
+                /* It's just a normal directory. */
+
+                r = image_new(IMAGE_DIRECTORY,
+                              pretty,
+                              path,
+                              filename,
+                              read_only,
+                              0,
+                              0,
+                              ret);
+                if (r < 0)
+                        return r;
+
+                return 1;
+
+        } else if (S_ISREG(st.st_mode) && endswith(filename, ".gpt")) {
+                usec_t crtime = 0;
+
+                /* It's a GPT block device */
+
+                if (!ret)
+                        return 1;
+
+                fd_getcrtime_at(dfd, filename, &crtime, 0);
+
+                if (!pretty)
+                        pretty = strndupa(filename, strlen(filename) - 4);
+
+                r = image_new(IMAGE_GPT,
+                              pretty,
+                              path,
+                              filename,
+                              !(st.st_mode & 0222) || read_only,
+                              crtime,
+                              timespec_load(&st.st_mtim),
+                              ret);
+                if (r < 0)
+                        return r;
+
+                return 1;
+        }
+
+        return 0;
+}
+
+int image_find(const char *name, Image **ret) {
+        const char *path;
+        int r;
+
+        assert(name);
+
+        /* There are no images with invalid names */
+        if (!image_name_is_valid(name))
+                return 0;
+
+        NULSTR_FOREACH(path, image_search_path) {
+                _cleanup_closedir_ DIR *d = NULL;
+
+                d = opendir(path);
+                if (!d) {
+                        if (errno == ENOENT)
+                                continue;
+
+                        return -errno;
+                }
+
+                r = image_make(NULL, dirfd(d), path, name, ret);
+                if (r == 0 || r == -ENOENT) {
+                        _cleanup_free_ char *gpt = NULL;
+
+                        gpt = strappend(name, ".gpt");
+                        if (!gpt)
+                                return -ENOMEM;
+
+                        r = image_make(NULL, dirfd(d), path, gpt, ret);
+                        if (r == 0 || r == -ENOENT)
+                                continue;
+                }
+                if (r < 0)
+                        return r;
+
+                return 1;
+        }
+
+        if (streq(name, ".host"))
+                return image_make(".host", AT_FDCWD, NULL, "/", ret);
+
+        return 0;
+};
+
+int image_discover(Hashmap *h) {
+        const char *path;
+        int r;
+
+        assert(h);
+
+        NULSTR_FOREACH(path, image_search_path) {
+                _cleanup_closedir_ DIR *d = NULL;
+                struct dirent *de;
+
+                d = opendir(path);
+                if (!d) {
+                        if (errno == ENOENT)
+                                continue;
+
+                        return -errno;
+                }
+
+                FOREACH_DIRENT_ALL(de, d, return -errno) {
+                        _cleanup_(image_unrefp) Image *image = NULL;
+
+                        if (!image_name_is_valid(de->d_name))
+                                continue;
+
+                        if (hashmap_contains(h, de->d_name))
+                                continue;
+
+                        r = image_make(NULL, dirfd(d), path, de->d_name, &image);
+                        if (r == 0 || r == -ENOENT)
+                                continue;
+                        if (r < 0)
+                                return r;
+
+                        r = hashmap_put(h, image->name, image);
+                        if (r < 0)
+                                return r;
+
+                        image = NULL;
+                }
+        }
+
+        if (!hashmap_contains(h, ".host")) {
+                _cleanup_(image_unrefp) Image *image = NULL;
+
+                r = image_make(".host", AT_FDCWD, NULL, "/", &image);
+                if (r < 0)
+                        return r;
+
+                r = hashmap_put(h, image->name, image);
+                if (r < 0)
+                        return r;
+
+                image = NULL;
+
+        }
+
+        return 0;
+}
+
+void image_hashmap_free(Hashmap *map) {
+        Image *i;
+
+        while ((i = hashmap_steal_first(map)))
+                image_unref(i);
+
+        hashmap_free(map);
+}
+
+static const char* const image_type_table[_IMAGE_TYPE_MAX] = {
+        [IMAGE_DIRECTORY] = "directory",
+        [IMAGE_SUBVOLUME] = "subvolume",
+        [IMAGE_GPT] = "gpt",
+};
+
+DEFINE_STRING_TABLE_LOOKUP(image_type, ImageType);
diff --git a/src/shared/machine-image.h b/src/shared/machine-image.h
new file mode 100644
index 000000000..646598f9c
--- /dev/null
+++ b/src/shared/machine-image.h
@@ -0,0 +1,55 @@
+/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
+
+#pragma once
+
+/***
+  This file is part of systemd.
+
+  Copyright 2014 Lennart Poettering
+
+  systemd is free software; you can redistribute it and/or modify it
+  under the terms of the GNU Lesser General Public License as published by
+  the Free Software Foundation; either version 2.1 of the License, or
+  (at your option) any later version.
+
+  systemd is distributed in the hope that it will be useful, but
+  WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+  Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public License
+  along with systemd; If not, see <http://www.gnu.org/licenses/>.
+***/
+
+#include "time-util.h"
+#include "hashmap.h"
+
+typedef enum ImageType {
+        IMAGE_DIRECTORY,
+        IMAGE_SUBVOLUME,
+        IMAGE_GPT,
+        _IMAGE_TYPE_MAX,
+        _IMAGE_TYPE_INVALID = -1
+} ImageType;
+
+typedef struct Image {
+        ImageType type;
+        char *name;
+        char *path;
+        bool read_only;
+
+        usec_t crtime;
+        usec_t mtime;
+} Image;
+
+Image *image_unref(Image *i);
+void image_hashmap_free(Hashmap *map);
+
+DEFINE_TRIVIAL_CLEANUP_FUNC(Image*, image_unref);
+DEFINE_TRIVIAL_CLEANUP_FUNC(Hashmap*, image_hashmap_free);
+
+int image_find(const char *name, Image **ret);
+int image_discover(Hashmap *map);
+
+const char* image_type_to_string(ImageType t) _const_;
+ImageType image_type_from_string(const char *s) _pure_;